The Senate voted unanimously on Thursday to ban its own members, their staffs, and chamber officers from trading on prediction markets, a swift bipartisan response to mounting evidence that people with access to sensitive government information have been cashing in on platforms like Kalshi and Polymarket.
Sen. Bernie Moreno, the Ohio Republican who sponsored the measure, framed the vote in blunt terms. The resolution passed by voice vote and, because it was written as a change to Senate rules, took effect immediately.
That immediacy matters. The ban did not need to clear the House or land on the president's desk. It is now the law of the Senate chamber. And it arrived against a backdrop of real-world cases that made the status quo indefensible.
Reports indicate that at least 16 accounts made more than $100,000 each after correctly predicting a February strike against Iran, placing their bets hours before a surprise American and Israeli attack on top Iranian officials, including Iranian Supreme Leader Ayatollah Ali Khamenei. When anonymous traders are raking in six figures by anticipating military operations before the public knows anything, the question of insider knowledge stops being theoretical.
Sen. Elissa Slotkin, a Michigan Democrat and former CIA analyst, described the potential for insider trading on these platforms as an "operational risk." That is intelligence-community language for a threat that could compromise missions and get people killed.
The Iran bets were not the only alarm. A U.S. Army Special Forces soldier who took part in the operation to capture Venezuelan President Nicolás Maduro was accused of using classified information to earn more than $400,000 on Polymarket by predicting Maduro's demise. The soldier has pleaded not guilty to charges of disclosure of classified information and could face up to ten years in prison for each count.
That case put the problem in sharp relief. If a soldier with a security clearance could allegedly monetize battlefield intelligence on a betting platform, what stops a senator, or a Senate staffer briefed on classified operations, from doing the same?
Moreno, who flipped a Democratic-held Ohio seat in 2024, did not mince words when the bill passed. As Breitbart reported, the freshman senator cast the issue as a basic question of public trust:
"United States Senators have no business engaging in speculative activities like prediction markets while collecting a taxpayer-funded paycheck, period."
He followed up with a line that landed harder than most Senate floor rhetoric:
"Serving in Congress is an honor, not a side hustle. Americans deserve to know that their leaders are here for the right reason."
That framing, honor versus hustle, is the kind of plain-spoken accountability talk that resonates far beyond Capitol Hill. Congress has spent years dodging serious reform of its own financial conflicts. The STOCK Act, passed in 2012 to curb insider stock trading by lawmakers, has been riddled with enforcement gaps and ethics complaints ever since. Prediction markets represent a newer, faster, and potentially even more dangerous avenue for the same abuse.
The unanimous vote is itself notable in a chamber that can barely agree on lunch orders. Senate Minority Leader Chuck Schumer backed the measure from the Democratic side.
"We must never allow Congress to turn into a casino where members representing the public can gamble on wars or economic crises or elections."
An amendment from Sen. Alex Padilla expanded the original resolution to cover Senate officers and employees, not just the 100 senators themselves. Padilla's amendment also urged the House, the executive branch, and the judiciary to adopt similar self-regulation. Whether those other branches follow through remains an open question.
The fact that both parties moved together, and quickly, suggests the political risk of inaction outweighed any ideological objection. Prediction markets have gained popularity across the political spectrum. Polymarket, in particular, drew enormous attention during the 2024 election cycle. But popularity does not override the basic principle that people entrusted with classified briefings and legislative power should not be placing side bets on the outcomes they help shape.
In a Congress that has struggled to pass even routine legislation, as seen in recent House battles over FISA and budget bills, a unanimous Senate voice vote stands out. It suggests that the underlying facts were too damning for anyone to defend the status quo.
Both Kalshi and Polymarket said they support the Senate measure. Kalshi's top executive, Tarek Mansour, told reporters the company already "proactively blocks members of Congress" from its platform. Kalshi spokeswoman Elisabeth Diana described a screening tool the company uses, a "politically exposed persons' list", to filter out individuals likely to possess insider information.
"If they hit that list, they can't trade."
That sounds reassuring. But the track record tells a different story. Just last week, Kalshi sanctioned three political candidates for attempting to make trades on their own bids for Congress. If the platforms' existing safeguards were working, those candidates would never have gotten close to placing a bet.
The gap between what companies say their compliance systems do and what actually happens on their platforms is a familiar problem. Self-regulation has limits. The Senate, to its credit, decided not to wait for the industry to police itself.
The resolution changes Senate rules. It does not bind the House of Representatives, the executive branch, or the federal judiciary. Padilla's amendment urged those institutions to follow suit, but urging is not requiring. A House member with access to the same classified briefings as a senator faces no new restriction under this measure. Neither does a White House staffer, a Pentagon official, or a federal judge.
The bill's formal title and number were not specified in available reporting. Whether the resolution carries any enforcement mechanism beyond the Senate Ethics Committee's existing authority is also unclear. Senate rules changes can be powerful, they take effect immediately and do not require presidential signature, but they depend on the institution's willingness to police its own.
Given Congress's spotty record on self-enforcement, skepticism is warranted. The STOCK Act's history is a cautionary tale. Lawmakers passed it with fanfare, then quietly gutted key disclosure provisions months later. Whether this prediction-market ban avoids the same fate will depend on whether the Senate treats violations seriously, or treats the resolution as a press release.
The political dynamics surrounding the Iran strike and its aftermath only heighten the stakes. When traders can profit by anticipating American military action, the integrity of the entire national-security apparatus is on the line.
Moreno has been in the Senate for barely a year. That a freshman from Ohio, not a committee chairman, not a party leader, drove this measure to unanimous passage says something about where the energy for reform actually lives. The resolution amends Senate rules to prohibit lawmakers from entering agreements or transactions involving payment or delivery based on an event's outcome. That is a clean, enforceable standard.
It is also the kind of common-sense guardrail that most Americans assumed already existed. The fact that it didn't, that until Thursday, a sitting senator could legally bet on a prediction market while receiving classified intelligence briefings, is itself an indictment of how slowly Washington moves to close obvious conflicts of interest.
The broader landscape of congressional politics and ideological fights often buries straightforward accountability measures under partisan noise. This time, the noise stopped long enough for the right thing to happen.
The Senate did something rare: it identified a clear problem, wrote a clean fix, and passed it without a single dissent. The ban took effect the moment it passed. No implementation delay. No study commission. No six-month rulemaking window.
Now the question shifts to the House, where 435 members and thousands of staffers face the same temptations and the same access to sensitive information. If Speaker Johnson and House leadership let this sit, voters will draw their own conclusions about who is serious about clean government and who is not.
When the people who write the laws can bet on the outcomes they influence, the system is not just broken. It is rigged. The Senate closed one door on Thursday. The rest of the building is still wide open.